I made the present experiment in order to learn the various phases of testicular damages and the functional changes caused by the damages. 1) The methods chosen for stimulating the testicle were...a) as physical stimuli, high temperature (by the electric iron, ultra short waves), low temperature (by dry ice), isotope (P32, Co60), vasectomy, ischemia by ligation of blood vessels in spermatic cord...b) as chemical stimulants, maleic hydrazide, Trimeresurus venom...c) as hormonal stimulants, androgen, estrogen, bisteron, progesterone